Lightning rods are so last century: Next-gen lightning protection and harvesting with high-powered lasers

The standard way of protecting buildings (and their occupants) from lightning is pretty simple: You stick a lightning rod on the roof, and then some kind of conducting channel that takes the huge discharge of electricity and dumps it into the ground. This is a tried and tested method that is used by most of the world’s tall buildings. In the case of something vital like lightning protection, I’m usually a firm believer in “if it ain’t broke, don’t fix it” — but that was before I read about a new lightning protection system that uses lasers to redirect the lightning, so that it ignores the building entirely, instead taking a totally new route to ground or perhaps into a futuristic energy harvesting device.

The typical bolt of lightning carries around 5 billion joules (GJ, gigajoules) of energy, or the energy stored in 145 liters of gasoline. For comparison, a ton of TNT is around 4 gigajoules — so, we’re talking about quite a lot of energy here, concentrated in a very short period of time. Despite lightning protection systems, these strikes still cause around $1 billion in structural damage annually in the US — so there’s obviously space for improvement. Enter lasers. (Read: US Navy deploys laser weapon system that’s fired with ‘video game-like controller’.)

According to researchers at the University of Arizona and University of Central Florida, high-power lasers can be used to redirect the flow of lightning. As a general rule, lightning follows the path of least resistance (impedance) to the ground. A big metal rod, with wires running into the ground, has much lower resistance than air (which has very high electrical resistance) — and so the lightning chooses the rod. High-power lasers also don’t like to travel through air — but, when they do, they strip away electrons, leaving a wake of highly conductive ionized plasma. Lightning frickin’ loves travelling through plasma.

Externally refuelled optical filaments.The top image is high-power laser on its own; the bottom image is with the addition of a dressing beam.

The problem, though, is that lasers simply can’t travel very far through air without defocusing (a problem known as blooming, which we cover in our feature story about the science of beam weapons). To create a long enough channel of plasma — from the ground to the top of a building — the researchers had to devise a new method of beaming high-power lasers through air. The technical name of this method is called “externally refuelled optical filaments” [doi:10.1038/nphoton.2014.47], but in short they embed the high-powered beam (the filament) inside a low-power “dressing beam.” As the filament loses power, the dressing beam refuels it. “Think of two airplanes flying together, a small fighter jet accompanied by a large tanker,” says Maik Scheller, a University of Arizona researcher.

Lightning striking the Empire State Building three times. The ESB is struck by lightning roughly 25 times per year. This was a particularly unlucky night for the skyscraper. [Image credit]

All told, this technique allows the plasma column to be extended by “at least an order of magnitude.” In the lab, they increased the length of the plasma column from 10 inches to seven feet — in the real world, they think they could get to 165 feet. The idea is that, instead of sticking a lightning rod on top of the building, you would instead use a laser to produce a high-conductivity plasma channel. The researchers haven’t got as far as working out what a real-world installation would actually look like, but they seem positive that there are real, exciting applications for these refuelled optical filaments. If lightning really likes these plasma channels, there might also be a possibility of using them to guide the lightning towards some kind of energy harvesting apparatus.

As an aside, while researching this story I came across the electrolaser — a wondrously creative weapon that uses a laser to create a plasma column in air, and then uses that plasma channel to deliver a very strong electrical current. It is basically a long distance taser.

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MadisonHJ

Uh, why doesn’t someone just invent something to attach to the lightning rod to store the energy. No need for lasers and all those lightning rods that are in place now can be put to better use (not that they are not useful now).

Matthew Kent

Simplistically, nothing can store that much charge, that fast (that I am aware of). We would have to formulate some kind of new type of cap, which could hold the energy, then dissipate it to a battery. Yes, people have pondered this for a long time, but to my knowledge no one has found the proper metals, chemicals or method for doing this.

Just to update this and give you a concept of how much energy we are talking about. Lightening has been show to create anti-matter…

Avatar1337

The point was not to store the energy but to redirect it. It could even be used to discharge the clouds. That is, no point in waiting for lightning to strike. Just induce it.

ibwilliamsi

An average bolt of lightning, striking from cloud to ground, contains roughly one billion (1,000,000,000) joules of energy. This is enough to power a 60-watt light bulb for six months plus a forgotten open door refrigerator for a day.

It’s too much energy to redirect as well. At least with current (pardon the pun) technology. Trying to create technology that would store or redirect it is near to impossible because lightning is unpredictable and it tends to blow everything up or set it on fire. It’s not very cost effective to try to harness the energy of lightning when it only happens in the same place now and again (25 times a year at the ESB, per the article) and blows up your invention.

It’s more reliable to try to harness the rays of the sun or the swells of the ocean or the wind.

Magnus Blomberg

Also the rods are there all the time. I guess you don’t want to power the lasers all the time so then you have to be able to predict the lightning strikes in order to light up the lasers in time.

I don’t think this methode of diverting lightning has much promise for many years.

dc

yeah and lasers require power which often goes out during a storm. Sure you could have a backup battery supply, but that just adds to the cost of the system and makes it even less reliable.

Avatar1337

Unless you could make lightning to strike with this device. Maybe you could discharge the clouds, by pointing it upwards.

Jeff Vahrenkamp

Using a laser directs the lighting along the beam path which leads back to… the laser. I’m guessing 1-2 good lighting strikes might ruin the fancy light machine.

ackthbbft

I suspect the idea is if the source of the laser is not grounded, but the target of the laser is, then the lightning should still travel along that path of least resistance to the nearest ground state, which should then be the target and not the laser source. Another option might be for both the target and the source to have the same grounding point (basically a closed circuit) so that it doesn’t matter which end the lightning travels through, it would still eventually reach whatever storage device is created for the energy (provided there is some kind of protection at the laser source to collect that energy without affecting the actual laser device).

Timothy

The link doi:10.1038/nphoton.2014.47 does not work. I like this Idea, but I think it might cost to much to implement. Then you have to wait for a storm and say you get 1-2 strike’s in the storm you might harvest some electricicty. Would that be possible to offset the cost? Or do you think building an airship in the sky beaming down electricity would be more feasible. Maybe even a man made storm, I head that the Nasa’s space shuttle building is so tall that an atmosphere is created at the roof, and it could start raining inside if they didn’t properly ventilate it. Maybe it is possible to create your own storm inside a controlled building’s creating free energy. This is a great step, I just don’t think it would be used for the top of skyscraper’s that is all.

dc

Two problems: 1) A lightening rod is cheap. 2) lasers need energy and that sometimes isn’t available during a storm. Being from Florida, where we seem to lose power a lot (especially during those hurricane things), I wouldn’t trust a laser safety system, when a metal rod would work. Using it to harvest energy would be cool though, if it can be made to work. It still doesn’t seem like a reliable way to do it though as lightening can’t really be predicted.

thx1138v2

Lightning is caused by an imbalance of charges in the air versus the charges in the ground. When the imbalance becomes large enough it equalizes through the lightning strike. Benjamin Franlin’s lightning rod has a pointed end on the rod connected to the ground. This causes the air around the pointed end to ionize the air around it and this inoized air is the plasma that gives the lightning an easier path to the rod and then to the ground. But the fact is this pointed end actually attracts lightning, the thinking being it’s better to hit the rod and be channeled away to the ground than the building.

Nikola Tesla patented a lightning protection system in 1916 that mounts like a Franklin lightning rod on the top of buildings and has no sharp points but a larger surface area that continually equalizes the the charge in the air so the imbalance doesn’t occur in the first place and thus no lightning discharge is necessary to equalize the imbalanced charges. So it actually prevents lightning rather than just channeling it away.

No lasers, no hoopla, a completely passive system that just sits there and does it’s job. Seems the laser system is just reinventing the wheel once again. It’s basically the same as the Franklin system but uses lasers to create the ionized path. And if the laser or its driving circuit fails you then have an unprotected building.

Avatar1337

I actually had an idea like this. -_- should’ve patent it :/

Avatar1337

If they succeed the phaser gun will be made :)

Nathan Buchhop

Of would be a lot better to leave the rod as is but make it like a coil system and create an electro gun/transformer and down power the voltage to be able to be stored

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